The invention relates to a method for storing hazardous liquids which is economical, modular and requires less construction at the storage site.
The longstanding rationale to bury storage tanks for flammable liquids is to prevent the propogation of flame or explosion originating in or near one of the tanks in a multi-tank storage facility, and to isolate the storage tank from sources of ignition. Solvent loss due to evaporation is also reduced is the tanks are buried because the tanks are protected from direct sunlight and peak daytime temperatures. The disadvantages of direct burial of the tanks include the need to remove and dispose of large amounts of soil during construction, the difficulty in detecting leakage from the tanks and monitoring ground water contamination, no ground water protection in the event of a rupture or spill, little or no access for maintenance, and higher cost compared to above ground installation of isolated tanks. Also, it is not practical to provide underground storage systems when only temporary storage is needed at a site.
Prior art to deal with the environmental disadvantages include underground basins of concrete or impermeable soil, encasing above ground tank farms in large concrete vaults filled with gravel, compartmentalized buildings with a tank in each compartment, and gravel filled concrete basins on legs or "stilts". All of these approaches are extremely expensive, require ever more careful, extensive, and time consuming site preparation, and are difficult to enlarge or modify once in place. Elaborate means are still required (if feasible) to detect and contain leakage from individual tanks. Also, each installation is unique and requires permits from governmental agencies that are detailed and time consuming to prepare and be approved.